Image registration techniques play an important role in terrain assessment and mapping. From a sequence of geographically overlapping digital images, image registration techniques identify and automatically register points of correspondence ("tie points") among the plurality of images. These images are digital images with different orientations and/or scales. These images may also have been obtained at differing times of year and from different geographical perspectives.
Once tie points are identified, coordinates of each corresponding point in each image are calculated so as to be invariant with respect to the scale, orientation and position of the image of which the points are a part. From this information, the areas in common of the overlapping images can be analyzed. It may be desirable to assemble a single large image based on a collection of all of the overlapping points. Thus, a need has arisen to provide a method and apparatus for automatically identifying the same geographical points in different digital images having common coverage in a more versatile and useful fashion.